US2415992A - Gas pressure reducing means - Google Patents

Description

Feb. 18, 1947. 1.. c. CLAIR 2,415,992

GAS PRESSURE REDUCING MEANS Filed Sept. 25, 1943 Enventor Gttorneg Patented FebflS, .1947

UNITED STATES PATENT OFFICE GAS PRESSURE REDUCING MEANS Louis C. Clair, Palestine, Tex.

Application September 25, 1943, Serial No. 503,860

' Claims. 1

My invention relates to gas pressure reducingmeans and more particularly to gas pressure reducing equipment employing chokes.

An objectof my invention is to provide a gas pressure reducing means including a choke and an expansion chamber wherein the expansion chamber and the choke are formed into a single removable unit.

Another object of my invention is to provide a gas pressure reducing means including a choke and an expansion chamber for use in gas wells or other sources of high pressure gas designed to use the latent heat of the high pressure gas to prevent the choke and expansion chamber from freezing up and clogging due to the expansion of the high pressure gas in the expansion chamber.

Other objects and advantages of my invention will become apparent from a reading of my detailed description to follow of the gas pressure reducing means embodying my invention which is illustrated in my accompanying drawing.

In the majority of gas wells the delivered pressure of the gas at the well, that is to say the pressure of the gas as it is drawn from the tubing of the well, is greatly in excess of the gas pressure maintained in the main into which the gas is delivered. This fact necessitates the use of reducing'valves or the like to lower the pressure of the gas from the high well pressure to the lower pressure in the main. The pressure of gas in gas wells often runs as high as 2,000 pounds per square inch and sometimes higher, whereas the pressure in the gas main will run about 350 pounds per square inch more or less dependent upon the condition of the load on the gas main.

Chokes have long been used as separate means for reducing gas pressures or combined into more complicated gas pressure reducing mechanisms. The serious drawback to their. use, however, is the extreme cooling effect produced by the expansion of the gas after it passes through the choke and into an expansion chamber. The high pressure natural gas has some water in it. It is this water that causes the trouble when it turns into ice and collects on the wall of the expansion chamber and builds back to the choke to such an extent that the ice completely closes the choke. The temperature of the expanded gas will often drop below 0 Fahrenheit. Many attempts have been made to overcome this serious condtion in the use of chokes such as the location of the choke on the lower end of the gas tubing at or near the gas producing formation. Where a high pressure main is run above ground the sun's rays add heat to the high pressure gas to help the situation. but

2 this is only a slight help and is obviously of little advantage in the winter time. Sometimes such high pressure mains are heated with gas flames immediately -before the choke to increase the latent heat of the high pressure gas in an attempt to prevent freezing beyond the choke.

As far as applicant is aware none of these prior methods and constructions has proven satisfacto y because they were inadequate and inconvenient to use. My invention brings to the art of gas pressure reducing means a simple, emcient and convenient device that may be used singly as a gas pressure reducing means or combined into prior art and future gas pressure reducing mechanisms.

In the drawing:

Figure 1 is an elevation view showing a gas well equipped with a gas pressure reducer construction embodying my invention and,

Figure 2 is an enlarged cross sectional view of the gas pressure reducer construction shown in Figure 1.

In the drawing the letter C designates a gas well casing onto which is mounted a combination of control valves known to the gas industry as a Christma tree designated in the drawing by the letter T. My gas pressure reducing means is attached to the Christmas tree T beyond its upper right hand high pressure control valve H which high pressure control valve controls the high pressure gas G11 delivered by the tubing M. As this specification is not concerned with the Christmas tree T beyond its function as a means for delivering the high pressure gas Gh from the tubing Mto my gas pressure reducer construction. to be described later, there is no need for a detailed description of it in this specification. The reader should understand that my pressurereducer could be attached at any of the other openings of the Christmas tree T if desired, preferably beyond a control valve such as the control valve H so that the high pressure gas G11 can be easily shut ofl to permit changes to be made in my gas pressure reducer. I also recommend the use of a valve L to shut off the low pressure gas G1 in the gas main conveniently near to my gas pressure reducer to facilitate changes in it.

My gas pressure reducer includes a housing i which may be a T fitting. The housing I is connected to the Christmas tree T by means of an entrance nipple 2. The upper end of the housing I. as seen in Figure 1, or right end, as seen in Figure 2, is provided with an inspection opening that is closed by means of a bull plug 3. Into the lower end'of the housing, as seen in Figure 1, or

' the choke plug C is screwed.

The choke plug I combines in one unit 'a choke structure I and an expansion chamber I defined by the expansion chamber wall 0. The choke plugfi is provided with a slot H in its choke end for convenience in screwing the choke plug} into and out of the exit nipple 4. When the bull plug 3 is removed the operator has easy access to the slot II and may by means oi it turn the choke plug 3 with a screw driver or similarly shaped tool. changes in choke plugs 6 having bores of varying sizes to be used dependent upon the drop in gas pressure desired. t

The reader will notice that all of the choke structure! of the choke plug 6 and a substantial part of the expansion chamber wall 8 are positioned within the volume of high pressure gas (311. It is because of this location of the choke plug 6 that it isheated by the high pressure gas G The high pressure gas Ga as delivered from the Christmas tree T has a temperature of about 7 70 Fahrenheit. The reader will also notice that the choke plug 8 is extendedina direction crosswise of the flow of the high pressure gas Ga. By this arrangement oi. the choke plug 8- I compel the high pressure gas G11 to impinge on the choke plug 8 and give up. heat to it before the high pressure gas Gt isaliowed to pass through the orifice M of the choke plug 8 into the expansion chamber 8. Heat accumulated in the choke structure portion 1 of the choke plug 6 flows by conduction to the expansion chamber wall 9 which is being cooled by=the expansion of the high pressure gas Ga into the low pressure gas G1. In addition to this heat, ofcourse, the expansion chamber wall. 9 receives heat directly from the volume of high pressure gas Gn surrounding it. Heat is also conducted to the chamber wall 9 from the housing I passing through the threaded inner end of the exit nipple I.

While these quantities of heat are not sufllcient to overcome the complete refrigerating eflect of the expanding gas as it is converted from high pressure gas G11 to low pressure gas G1, they are sufficient to maintain the temperature of the expansion chamber wall I above the freezing point of water and thus prevent the accumulation of ice from creeping back into the expansion chamber 8 and choking of! the flow of the high pressure gas Gn through the orifice ill of the choke plug 6. The accumulation of ice in the exitnipple 4 and succeeding portions of the low pressure line not shown is not serious because the accumulation of ice there is spread over considerable area and in a portion or the low pressure line" where itsdiameter is relatively large.

This arrangement makes convenient:

' member adapted to conduct high pressure gases It is to be understoodthat various changes in the size, shape and arrangement of parts of my above described gas pressure reducer may be resorted to within the scope of my invention;

Having thus described my invention, I claim: l. A gas pressure reducer comprising a housing with an entrance opening formed in-the side of the housing member and an exit opening formed in an end of the housing member. a choke including a bore adapted to conduct high pressure gas positioned within the housing member and a tubularvshell extending from the choke in alignment with the bore oi. the choke and in communication with the hereof the choke, said tubular shell defining an expansion chamber and means for preventing the choke bore from freezing due to the expansion of gas in said expansion chamher which includes means for mounting one end or the tubular shell in the exit opening oi? said housing with a major portion of its length in spaced relation to thehousing member and in the path oi! the gas coming through the entrance opening to permit said gas to circulate around the tubular shell before it passes through the bore of the choke.

2. The device as claimed in claim 1 wherein the choke and shell are made as a unit and wherein the choke and shell unit is releasably engaged with the housing member and wherein the housing member is provided with an inspection opening positioned opposite the choke end of the choke and shell unit and being oi. a diameter greater than the diameter of the choke and shell unit to permit its removal and a plug for closing the inspection opening.

3. The device as claimed in claim 1' wherein the choke extends crosswise oi the entrance opening of the housing member. I

4. The device as claimed in claim 1 wherein the tubular shell extends crosswise of the ena trance opening of the housing member.

\ 5. The device as claimed in claim 1 wherein the choke and the tubular shell extend crosswise of the entrance opening of the housing member.

LOUIS C. CLAIR.

REFERENCES CITED The following references are of record in the file of thispatent:

, UNITED STATES PATENTS Number Michalk July 17, 1906

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